Re: Hardened valve seats or lead additive...

Posted by Craig Hendrickson On 2012/11/27 23:28:14

S8 I'm not sure.

V-8 for sure hardened exhaust seats. I have previously posted a chart that says that if you cruise at 60+ for extended periods, then your non-hardened seats will be beat down. I personally experienced this. Since I replaced the V-8 heads & with hardened seats, I've had no problems and that's been about 10 years at extended high speeds, of which the V-8s are more than capable.

For an example, see KevinAZ's 1955 400 turning "back to zero" odometer whilst cruising at 80+MPH on the last PackardInfo.com meet to/from 900 mile trip. His engine has hardened inserts on the exhaust seats, so he should be able to do that high speed cruising for years and 10's of thousands of miles.

Craig